Alkylpolyglucoside with a high degree of oligomerization

ABSTRACT

The present invention provides a defined alkylpolyglucoside having a degree of oligomerization of at least 1.7 to 3 and an alkyl radical comprising 8 carbon atoms, and mixtures of this alkylpolyglucoside with further alkylpolyglucosides, as cleaner concentrate. The present invention also relates to compositions which include the defined alkylpolyglucoside and a concentrated alkali metal hydroxide solution as well as a method of using the composition as a cleaner.

FIELD OF THE INVENTION

[0001] The present invention relates to a defined alkylpolyglucoside, tomixtures of this alkylpolyglucoside with other alkylpolyglucosides, andto the use of these alkylpolyglucosides as a cleaner concentrate.

BACKGROUND OF THE INVENTION

[0002] Cleaning in place procedure is usually carried out using highlyconcentrated industrial alkaline hydroxide solutions, for example, 50%strength by weight sodium hydroxide solution or 45% strength by weightpotassium hydroxide solution. In the corresponding works, for example, abrewery or dairy, this cleaner concentrate is diluted to customary useconcentrations for the appropriate application. To increase the cleaningperformance, further surfactants are customarily used.

[0003] From WO 99/21948, it is known that alkylpolyglucosides with hexylsubstitution are stable in concentrated alkali metal hydroxidesolutions. Thus, in the table on Page 8 of WO'948, an n-hexylglucosideis described which gave a clear solution even in 40% strength by weightsodium hydroxide solution at a concentration of 7.5%. Data on the degreeof oligomerization (DP) are not contained in this publication.

[0004] The product described in United States Statutory InventionRegistration H171 is likewise unsuitable for combination with highlyconcentrated alkali metal hydroxide solutions.

[0005] DE-A-196 07 753 describes alkylpolyglucosides with a high degreeof oligomerization as high-performance surfactants for liquid detergentsand cleaners. It is described in the '753 publication how suitablealkylpolyglucosides are accessible by processing fatty alcohols andglucose in a molar ratio of 3:1 to 10:1 at temperatures in the rangefrom 90° to 120° C. in an acid-catalyzed acetalation with continuousremoval of the water of reaction by distillation to givealkyloligoglucosides with a low degree of oligomerization (<1.6), and,following termination of the reaction, neutralizing the acidic catalystto 0 to 90 mol %.

[0006] Following removal of such an amount of unreacted fatty alcohol,which regulates the molar ratio of the remaining fatty alcohol andglucose, based on the starting amount, to 1:1 to 3:1, the reactionmixture is subjected to post-polymerization at temperatures in the rangefrom 90° to 120° C.

[0007] Following neutralization of the remaining amount of the acidiccatalyst and removal of the unreacted fatty alcohol,alkyloligoglucosides are obtained which have a degree of oligomerizationin the range from 1.6 to 2.5, in particular 1.6 to 2, without theproducts being burdened by too high a polyglucose content or inadequatecolor quality. In the '753 publication, it was possible to reduce thepolyglucose fraction to below 5%.

[0008] Typical examples of fatty alcohols which may be used as startingmaterial in the process are caproic alcohol, caprylic alcohol,2-ethylhexyl alcohol, capric alcohol, lauryl alcohol, isotridecylalcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, isostearylalcohol and behenyl alcohol, and mixtures thereof, which are produced,for example, during high-pressure hydrogenation of technical-grademethyl esters based on fats and oils or aldehydes from the Roelen oxosynthesis, and as monomer fraction during the dimerization ofunsaturated fatty alcohols.

[0009] Particularly preferred technical-grade fatty alcohols are thosehaving 8 to 10, or 12 to 18 carbon atoms, in particular hydrogenatedforerun, coconut, palm, palm kernel or tallow fatty alcohol.

[0010] The acidic catalysts used are, in particular, sulfuric acid,alkylsulfuric monoesters, alkyklbenzenesulfonic acid, such as, forexample, p-toluenesulfonic acid or dodecylbenzenesulfonic acid andsulfosuccinic acid. The amounts used are usually in the range from 0.1to 5% by weight, preferably 0.5 to 2% by weight, based on the substancesused.

[0011] However, the surfactants specifically disclosed in the '753publication are not suitable for highly concentrated alkaline cleanerconcentrates.

[0012] Accordingly, there is a need to provide a highly stablepolyalkylglucoside which is stable in commercially availableconcentrated technical-grade alkali metal hydroxide solutions and at thesame time has good emulsifying power.

SUMMARY OF THE INVENTION

[0013] The above object is achieved according to the present inventionby providing an alkylpolyglucoside having a degree of oligomerization(DP) of at least 1.7 to 3, where the alkyl radical comprises 8 carbonatoms. Thus, according to the present invention, ethylhexylglucosidewith a degree of oligomerization in the range from 1.7 to 3 isdescribed.

DETAILED DESCRIPTION OF THE INVENTION

[0014] Surprisingly, it has been found that the alkylpolyglucoside ofthe present invention has long-term stability even in highlyconcentrated alkali metal hydroxide solutions based on sodium hydroxidesolution or potassium hydroxide solution and does not lead toprecipitations. The emulsifying power is also good in dilute alkalinecleaner solutions.

[0015] The alkylpolyglucoside according to the present invention isobtainable by a process described in detail in DE-A- 196 07 753. In thisrespect, the entire contents of the '753 publication are incorporatedherein by reference.

[0016] In a preferred embodiment of the present invention, thealkylpolyglucoside according to the present invention has a degree ofoligomerization (DP) of from 1.85 to 2.5.

[0017] In the prior art, it is known to use cleaner concentrates basedon alkylpolyglucosides having alkyl radicals in which the number ofcarbon atoms in the alkyl radical is other than 8 (see, for example,DE-A-196 07 753). Thus, the prior art discloses alkylpolyglucosideshaving an alkyl radical which comprises, in particular, 6 to 24 carbonatoms. These alkylpolyglucosides known per se can be used for thepurposes of the present invention in combination withethylhexylglucoside. For the purposes of the present invention,particular preference is therefore given to mixtures ofalkylpolyglucosides of different origin than the ethylhexylglucoside,the weight ratio of the ethylhexylglucoside to the otheralkylpolyglucosides being adjusted such that at least 50% by weight ofthe alkylpolyglucoside consist of ethylhexylglucoside.

[0018] To use the alkylpolyglucoside according to the present inventionand mixtures of the inventive alkylpolyglucoside with otheralkylpolyglucosides, the inventive alkylpolyglucosides are admixed withconcentrated technical-grade alkali metal hydroxide solution.Commercially available technical-grade concentrated alkali metalhydroxide solutions include, for example, 50% by weight of NaOH or 45%by weight of KOH in water.

[0019] For the purposes of the present invention, particular preferenceis therefore given to mixtures of one or more of saidalkylpolyglucosides with technical-grade concentrated alkali metalhydroxide solutions, said mixtures comprising 50 to 99.9% by weight ofconcentrated alkali metal hydroxide solutions and 0.1 to 50% by weightof the alkylpolyglucosides. For the purposes of the present invention,particular preference is given to corresponding mixtures which comprise90 to 99.9% by weight of technical-grade concentrated alkali metalhydroxide solutions and 0.1 to 10% by weight of the alkylpolyglucosides.

[0020] For the purposes of the present invention, particular preferenceis given to the above-mentioned cleaner concentrate for the cleaning ofsurfaces in breweries and dairies.

[0021] The alkylpolyglucoside according to the invention is considerablyless foaming, although the surface activity is not adversely affected.

[0022] The following examples are given to illustrate the presentinvention as well as show some advantages that are obtained therefrom.Working examples:

EXAMPLE 1 Comparative Examples 1 to 7

[0023] The alkylpolyglucosides (APG) given in Table 1 below wereprepared analogously to DE 196 07 753 A1: TABLE 1 Degree of Examples:Compound: oligomerization: Example 1 EthylhexylPG approx. 2.0Comparative example 1 EthylhexylPG approx. 1.1 Comparative example 2EthylhexylPG approx. 1.3 Comparative example 3 EthylhexylPG approx. 1.6Comparative example 4 Ethylhexyl-/Decyl-PG approx. 1.5 Comparativeexample 5 Octyl-decyl-PG approx. 1.6 Comparative example 6Octyl-decyl-PG approx. 1.6 Comparative example 7 Octyl-decyl-PG approx.1.6

[0024] In Table 2 below, the solubility behavior of the above-describedalkylpolyglucosides in concentrated aqueous sodium hydroxide solutionwas investigated: TABLE 2 Dissolved in % by weight of NaOH Examples: 1520 25 30 35 40 50 Example 1 + + + + + + + Comparative example 1 + − − −− − − Comparative example 2 + + − − − − − Comparative example 3 + + + −− − − Comparative example 4 + + + + + ± − Comparative example 5 + + ± −− − − Comparative example 6 + + + − − − − Comparative example 7 + + + −− − −

[0025] The solubility in concentrated potassium hydroxide solution wasalso determined in an identical manner. The results are given here inTable 3: TABLE 3 Dissolved in % by weight of KOH Examples: 15 20 25 3035 40 45 Example 1 + + + + + + + Comparative example 4 + + + + + + ±

[0026] In a further test series, the emulsifiability of theabove-mentioned alkylpolyglucosides in a dilution of 1.0 g/l in oliveoil was determined:

[0027] The emulsifying power was determined by preparing a 1:1 mixturewith water and commercially available olive oil. 0.05% of thealkylpolyglucosides were added thereto and then mixed with vigorousshaking. The separation of oil was observed at different time intervals.The lower the oil separation, the more efficient the surfactant.

[0028] Using the alkylpolyglucosides of Comparative examples 1 to 3 and5 to 7, no emulsions could be obtained.

[0029] Table 4 below shows the data obtained: TABLE 4 % oil seperationExamples 30 min 1 h 2 h 3 h Example 1 2 4  8 12 Comparative example 4 16 10 20

[0030] The table below gives formulations of the alkaline cleaners witha maximum NaOH concentration: TABLE 5 Gluconic NaOH acid 50% 50% Amountof the Examples strength strength APG* Water Example 1* 80 10.0 5.0 —Comparative example 4* 70 10.0 5.0 ad 100 Comparative example 6 60 10.05.0 ad 100 Comparative example 7 60 10.0 5.0 ad 100

[0031] The table below gives the emulsifiability of alkaline cleaners inolive oil in a 1% strength dilution (comprises 0.5 g/l of the APG in thesolution tested): TABLE 6 % water seperation Examples 30 min 1 h 3 h 24h Example 1 0 0  8 40 Comparative example 4 0 0 12 54 Comparativeexample 6 0 0 10 50 Comparative example 7 0 0 14 56

[0032] The table below gives the emulsifiability of alkaline cleaners inolive oil in a 0.5% strength dilution (comprises 0.25 g/l of the APG inthe solution tested): TABLE 7 % water seperation Examples 30 min 1 h 3 h24 h Example 1 0 1 8 40 Comparative example 4 0 2 8 40

[0033] The table below gives the emulsifiability of alkaline cleaners inolive oil in a 0.25% strength dilution (comprises 0.125 g/l of he APG inthe solution tested): TABLE 8 % water seperation Examples 30 min 1 h 3 h24 h Example 1 0 1 6 30 Comparative example 4 0 2 6 30

[0034] The table below gives the emulsifiability of alkaline cleaners inolive oil in a 0. 1% strength dilution (comprises 0.05 g/l of The APG inthe solution tested): TABLE 7 % water seperation Examples 30 min 1 h 3 h24 h Example 1 0 2 6 0 Comparative example 4 0 2 6 4 ml oil

[0035] The table below gives the foaming behavior (DIN 53902) of 1.0 g/lof ethylhexylPG of varying degrees of DP:

[0036] The foaming ability was determined in accordance with DIN 53902Part 1, the procedure here being the perforated-plate impact procedurein the manual impact method.

[0037] A measuring cylinder (500 ml in size) with cm graduations wascharged with 250 ml of surfactant solution; this corresponded to aliquid level of 14 cm. The perforated plunger (disk diameter 45 mm with12 holes per 5 mm) was placed onto the cylinder and 20 uniform plungeswere made. The foam produced as a result was given in cm of foam height.The value directly after the plunging was given as the total height(liquid and foam), but in the case of the values for 30, 60 and 120seconds, only the actual foam height was given. TABLE 10 Foam height(cm) Examples Initially 30″ 60″ 120″ Example 1 10 1.5 1 1 Comparativeexample 1 14 2 1 1 Comparative example 2 13 2 1 1 Comparative example 312 1.5 1 1

[0038] The table below gives the foaming behavior (DIN 53902) ofalkaline cleaners containing the APG: TABLE 11 Foam height (cm) ExamplesConc. Initially 30″ 60″ 120″ Example 1* 0.50% 10  2 1 1 Comparativeexample 4* 0.50% 13 11 10 10 Example 1* 0.25%  8  1 0.5 0.5 Comparativeexample 4* 0.25%  9  7 6 6 Example 1* 0.10%  5  0 0 0 Comparativeexample 4* 0.10%  7  5 4 3.5

[0039] The table below gives the surface tension of 1.0 g/l ofethylhexylPG of varying degrees of DP:

[0040] A K10ST digital tensiometer from Krüss was used. The measurementbody used was a ring, in accordance with Du Nouy.

[0041] The platinum ring was immersed into the liquid to be investigatedand then drawn out again. The force required to pull the ring throughthe surface was measured. TABLE 12 Surface tension Examples (mN/cm)Example 1 33 Comparative example 1 34 Comparative example 2 33Comparative example 3 32

[0042] The table below gives the surface tension of alkaline cleanerscontaining the APG: TABLE 13 APG active Surface tension Examples Conc.ingredient content (mN/cm) Example 1* 0.50% 0.25 g/l 35 Comparativeexample 4* 0.50% 0.25 g/l 28 Example 1* 0.25% 0.125 g/l  43 Comparativeexample 4* 0.25% 0.125 g/l 30 Example 1* 0.10% 0.05 g/l 47 Comparativeexample 4* 0.10% 0.05 g/l 34

[0043] While the present invention has been particularly shown anddescribed with respect to preferred embodiments thereof, it will beunderstood by those skilled in the art that the foregoing and otherchanges in form and detail may be made without departing from the spiritand scope of the present invention. It is therefore intended that thepresent invention not be limited to the exact forms and detailsdescribed and illustrated but fall within the scope of the appendedclaims.

Having thus described our invention in detail, what we claim as new anddesire to secure by the Letters Patent is:
 1. An alkylpolyglucosideoligomer comprising an alkylpolyglucoside having a degree ofoligomerization (DP) of at least 1.7 to 3, where the alkyl radicalcomprises 8 carbon atoms.
 2. The alkylpolyglucoside oligomer of claim 1,wherein the degree of oligomerization (DP) is 1.85 to 2.5.
 3. Acomposition comprising a mixture of an alkylpolyglucoside of claim 1 andat least one additional alkylpolyglucoside having an alkyl radical whichcomprises 6 to 24 carbon atoms.
 4. The composition of claim 3, whereinthe weight ratio of the alkylpolyglucoside having 8 carbon atoms to thealkylpolyglucoside having 6 to 24 carbon atoms is adjusted such that atleast 50% by weight of the alkylpolyglucosides compriseethylhexylglucoside.
 5. A composition comprising a mixture of one ormore alkylpolyglucosides of claim 1 and a concentrated alkali metalhydroxide solution.
 6. The mixture of claim 5, which comprises 50 to99.9% by weight of said concentrated alkali metal hydroxide solution and0.1 to 50% by weight of said alkylpolyglucosides.
 7. The mixture ofclaim 5, which comprises 90 to 99.9% by weight of said concentratedalkali metal hydroxide solution and 0.1 to 10% by weight of saidalkylpolyglucosides.
 8. The mixture of claim 3 wherein saidalkylpolyglucoside having 8 carbon atoms has a degree of oligomarizationof 1.85 to 2.5.
 9. A method for industrial cleaning surfaces comprising:applying a composition comprising an alkylpolyglucoside having a degreeof oligomerization of at least 1.7 to 3, wherein the alkyl radicalcomprises 8 carbon atoms and a concentrated alkali metal hydroxidesolution to a surface requiring cleaning.
 10. The method of claim 9which comprises 50 to 99.9% by weight of said concentrated alkali metalhydroxide solution and 0.1 to 50% by weight of said alkylpolyglucoside.11. The method of claim 10 which comprises 90 to 99.9% by weight of saidconcentrated alkali metal hydroxide solution and 0.1 to 10% by weight ofsaid alkylpolyglucoside.
 12. The method of claim 9 further comprising atleast one additional alkylpolyglucosides having an alkyl radical having6 to 24 carbon atoms.
 13. The method of claim 12, wherein the weightratio of the alkylpolyglucoside having 8 carbon atoms to thealkylpolyglucoside having 6 to 24 carbon atoms is adjusted such that atleast 50% by weight of the alkylpolyglucosides compriseethylhexylglucoside.